The overall goal of this project is to improve the use of apnea monitoring for infants at increased risk for SIDS. The studies will be carried out in 1) premature infants under 1500 grams birth weight and those less than 15OO grams who exhibit repetitive prolonged apnea at the time of discharge from the hospital. 2) infants with an apparent life threatening event (ALTE) for which no cause can be identified and 3) subsequent siblings of SIDS. These infants will participate in a program involving home monitoring of apnea, bradycardia and oxygen with computer storage of these events. They will also undergo systematic laboratory polysomnographic evaluations. Our specific aims are the following: 1a. To identify the infants who may benefit from event recordings or, alternatively, those infants who do not seem to need event recordings. 1b. To evaluate current physiological criteria for event recordings and home monitoring in normal term and premature infants. 1c. To determine the physiological significance of the recorded events. 1d. With the help of systematic polysomnographic data, confirm or refute the conclusions reached about physiological risk patterns in infants who die of SIDS (prevalence of increased heart and breathing rates, obstructive apnea and decreased respiratory sinus arrhythmia). 1e. Obtain event recordings in a group of infants at low epidemiological risk for SIDS to determine normal and abnormal levels and decreases in oxygen saturation. 2a. To determine under what conditions alarms flag significant physiological events and when they represent artefacts. Simultaneous use of event recordings during polysomnography sessions would accomplish this objective as well as aid in calibration. 2b. With the help of systematic polysomnographic data, determine what significant patterns the event recorders currently fail to identify. 3a. To determine parental compliance with the monitoring program. 3b. To identify motivational factors that influence compliance. The Pediatric teaching hospitals at the University of Southern California serve a large population of socially disadvantaged, Hispanic women and infants. Because of our longstanding scientific and clinical work in SIDS, Children's Hospital, Los Angeles is the quintessential referral site for infants with ALTE from all racial and ethnic groups. Traditional close working relationships with chapters of the National SIDS Alliance and the Guild for Infant Survival guarantees substantial interest for this study by parents of SIDS.